Developments in modern internal combustion engines are continually being driven toward improved fuel efficiency and emissions reduction. For example, diesel engines can be downsized and have their speed capability reduced to improve efficiency. Spark-ignited engines that employ gaseous fuel and hybrid power trains that employ electric motors in addition to an engine are further examples of such developments to improve efficiencies and emissions performance.
However, there are drawbacks to these developments. For example, the transient response capability and engine braking performance of these engines suffer due to downspeeding, downsizing, lower compression ratio and/or Miller cycling to improve efficiencies. Therefore, further improvements in this area are needed.